2,4-Dihydroxybenzophenone
[CAS# 131-56-6]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic ketone
• Name: 2,4-Dihydroxybenzophenone
• Synonyms: Benzoresorcinol; (2,4-dihydroxyphenyl)phenyl-methanone
• Molecular Formula: C₁₃H₁₀O₃
• Molecular Weight: 214.22
• CAS Registry Number: 131-56-6
• EC Number: 205-029-4
• SMILES: C1=CC=C(C=C1)C(=O)C2=C(C=C(C=C2)O)O

Properties

• Solubility: insoluble (water)
• Density: 1.3±0.1 g/cm³, Calc.^*, 1.32 g/mL (Expl.)
• Melting point: 144.5-147 °C (Expl.)
• Index of Refraction: 1.648, Calc.^*
• Boiling Point: 409.0±14.0 °C (760 mmHg), Calc.^*, 194 °C (1 mmHg) (Expl.)
• Flash Point: 215.3±16.6 °C, Calc.^*, 125 °C (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Reproductive toxicity	Repr.	2	H361
Reproductive toxicity	Repr.	2	H361f
Skin sensitization	Skin Sens.	1A	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410

Discovery and Applications

2,4-Dihydroxybenzophenone, a member of the benzophenone family, is an organic compound known for its potent ultraviolet (UV) absorption properties. Its structure comprises a benzophenone core with hydroxyl groups at the 2 and 4 positions, enabling effective absorption of UV-A and UV-B radiation. This compound was discovered during early 20th-century investigations into aromatic ketones and their potential applications as UV stabilizers.

The discovery of 2,4-dihydroxybenzophenone stemmed from efforts to enhance the durability of materials exposed to sunlight. Chemists recognized that the hydroxyl groups in its structure facilitated strong interactions with UV radiation, converting it into harmless thermal energy. This property, coupled with the compound’s chemical stability, positioned it as a valuable additive for protecting a wide range of products from photodegradation.

2,4-Dihydroxybenzophenone is widely utilized as a UV absorber in the plastics and polymer industries. It is incorporated into materials such as polyvinyl chloride (PVC), polystyrene, and polycarbonate to prevent discoloration, loss of mechanical properties, and brittleness caused by prolonged sunlight exposure. Additionally, it is employed in coatings and varnishes to preserve surface aesthetics and integrity under UV-rich environments.

In personal care products, 2,4-dihydroxybenzophenone is a key ingredient in sunscreen formulations. Its ability to absorb harmful UV rays helps protect human skin from damage and premature aging. Beyond its use in consumer products, the compound is applied in specialty industries, including photography, where it stabilizes sensitive films and papers, and in electronics, where it safeguards optical components from UV-induced deterioration.

The continued development and application of 2,4-dihydroxybenzophenone highlight its importance in modern material science. Its versatility and efficacy as a UV absorber underscore its critical role in extending the lifespan and performance of various materials.

References

1965. Synthesis of Stabilizers for Polymer Materials. Aging and Stabilization of Polymers.
DOI: 10.1007/978-1-4615-8549-7_4

2023. Effect of beta-cyclodextrin on benzophenones and its impact on UVR filtration of cotton fabric through ‘guest absorber—host enhancer’ mechanism. Journal of Inclusion Phenomena and Macrocyclic Chemistry, 103(3).
DOI: 10.1007/s10847-023-01184-3

2024. Sunscreens in the aquatic environment and potential solutions for mitigation of sunscreen pollution. Euro-Mediterranean Journal for Environmental Integration, 9(3).
DOI: 10.1007/s41207-024-00655-4